Product Summary

A square coupling nut is typically a metal fastener which is threaded on the inside. It is designed to secure two parts together by screwing the coupling nut onto the outside of another part, often a threaded rod. The outside of a coupling nut is usually hex shaped so that a wrench can tighten or loosen it.

Square coupling nuts may be made out of any material, but the most common coupling nuts are metal due to the strength of the material and the variety of applications in which it may be used. Metal coupling nuts may be made out of stainless steel, carbon steel, brass or aluminum. In much rarer situations, they may be made out of PVC or similar materials.